High IV melt phase polyester polymer catalyzed with antimony containing compounds

ABSTRACT

A melt phase process for making a polyester polymer melt phase product by adding an antimony containing catalyst to the melt phase, polycondensing the melt containing said catalyst in the melt phase until the It.V. of the melt reaches at least 0.75 dL/g. Polyester polymer melt phase pellets containing antimony residues and having an It.V. of at least 0.75 dL/g are obtained without solid state polymerization. The polyester polymer pellets containing antimony residues and having an It.V. of at least 0.70 dL/g obtained without increasing the molecular weight of the melt phase product by solid state polymerization are fed to an extruder, melted to produce a molten polyester polymer, and extruded through a die to form shaped articles. The melt phase products and articles made thereby have low b* color and/or high L* brightness, and the reaction time to make the melt phase products is short.

1. FIELD OF THE INVENTION

This invention pertains to the manufacture of polyester polymers, andmore particularly to the manufacture of high It.V. polyethyleneterephthalate polymer and copolymers catalyzed with antimony compoundsin the melt phase having good color.

2. BACKGROUND OF THE INVENTION

In European patent application 1 188 783 A2 and U.S. Pat. No. 6,559,271,a process for making high IV PET in the melt phase is described. In thispatent, high IV PET catalyzed with a titanium based compound isdescribed as providing a good compromise between reactivity andselectivity when a low dosage of titanium metal and a low reactiontemperature is chosen to obtain optimal increase in molecular weight andreduce the chance of thermal decomposition. By providing a morethermally stable polymer, the level of acetaldehyde (“AA”) generated inthe polymer is reduced. The amount of AA generated by the describedprocess in the base polymer is not stated, but after addition of anexcess amount of AA bonding agent, the contemplated amount of AA in thepolymer melt is described as ranging from 1 to 10 ppm directly afterpolycondensation. Recognizing that AA bonding additives can cause astronger or weaker yellowing of the polyester polymer, the patentrecommends controlling the color imparted by the AA reducing additivesby adding bluing toners to the melt.

We have discovered that titanium catalyzed polycondensation reactionsimpart an unacceptably high yellow color to high It.V. base polyesterpolymers made in the melt phase as indicated by their high b*, a problemnot addressed by U.S. Pat. No. 6,559,271. Adding sufficient amount ofbluing toner to overcome the yellow color imparted to the melt by atitanium-catalyzed reaction presents the further problem of having touse higher amounts of bluing toners, which has the potential forreducing the brightness of the polymer and increases the costs formaking the polymer composition.

In order to reduce the level of AA in the melt phase polymer, theprocess described in U.S. Pat. No. 6,559,271 operates the melt phase ata reduced temperature and with a reduced titanium catalystconcentration, i.e. low reaction temperature on the order of 270° C. andless than 10 ppm Ti metal as the catalyst concentration. However, byreducing the reaction temperature and catalyst concentration, thereaction time required to attain the same target molecular weight alsoincreases.

It would be desirable to implement a solution to make a high It.V.polymer in the melt phase with a better, lower b* (a measure of theyellow hue in the polymer). Moreover, it would also be desirable toretain the same or better, shorter reaction times to a target high It.V.in the melt compared to the reaction time needed to obtain the sametarget It.V. in titanium-catalyzed reactions with an acceptable b*color.

3. SUMMARY OF THE INVENTION

We have found a process for making a high It.V. polyester polymer meltphase product in which the base polymer from the melt phase hasacceptable b* color. In the process, a polyester polymer made in themelt phase with high It.V. now has a better, lower b* color relative totitanium catalyzed reaction products at equivalent reaction times.Surprisingly, we have also discovered a process which allows for widelatitude of catalyst concentrations and polycondensation reactiontemperatures while simultaneously obtaining a base polyester polymerhaving lower b* relative to titanium catalyzed melt phase reactions. Wehave also discovered that in the process of the invention, the time ofreaction to obtain a high It.V. target is shorter than in atitanium-catalyzed process at low titanium catalyst dosages and lowreaction temperatures, even though titanium based catalysts are known tobe highly active.

There is now provided a melt phase process for making a polyesterpolymer melt phase product comprising adding an antimony containingcatalyst to the melt phase, polycondensing a melt containing saidcatalyst in the melt phase until the It.V. of the melt reaches at least0.75 dL/g.

There is also provided polyester polymer melt phase pellets having anIt.V. of at least 0.70 dL/g obtained without solid state polymerizationand containing antimony residues.

There is further provided a process comprising feeding to an extruder apolyester polymer composition comprising a melt phase product containingantimony residues and having an It.V. of at least 0.70 dL/g obtainedwithout increasing the molecular weight of the melt phase product bysolid state polymerization, melting the polyester polymer composition toproduce a molten polyester polymer, extruding the molten polyesterpolymer composition through a die to form shaped articles.

There is also provided a melt phase process for making a polyesterpolymer melt phase product containing at least 100 ppm antimony based onthe weight of the product comprising adding an antimony-containingcatalyst to the melt phase; polycondensing a melt containing saidcatalyst in the melt phase; and before the It.V. of the melt reaches0.45 dL/g, continuously polycondensing the melt either at a temperaturewithin a range of 265° C. to 305° C. or at sub-atmospheric pressure or acombination thereof, in each case until the It.V. of the melt reaches atleast 0.75 dL/g; to produce said polyester polymer melt phase producthaving a b* color in the range of −5 to +5 (CIELAB units). The colorunits are always in CIELAB units unless otherwise stated.

There is further provided a melt phase process for making a polyesterpolymer melt phase product comprising polycondensing a melt in thepresence of an antimony-containing catalyst to an It.V. of at least 0.75dL/g, wherein said product has a b* color of −5 to +5, and an L* of atleast 70. The melt phase product optionally contains a bluing tonerand/or a reheat enhancing aid made in situ, added to the melt, or addedafter solidifying the melt, or any combination thereof. The bluing toneris preferably an organic toner.

In yet another embodiment, there is provided a melt phase process formaking a polyester polymer melt phase product comprising:

a) esterifying or transesterifying a diol with a a carboxylic acidcomponent comprising dicarboxylic acids, dicarboxylic acid derivatives,and mixtures thereof to produce an oligomeric mixture;

b) polycondensing the oligomeric mixture to produce a polyester polymermelt having an It.V. of at least 0.75 dL/g; and

c) adding an antimony compound to the melt phase before the It.V. of thepolyester polymer melt reaches 0.45 dL/g; and

d) optionally adding a stabilizer to the melt phase;

wherein the polyester polymer melt phase product has a b* color of −5 to+5.

Preferably, polycondensation catalysts added to the polycondensationzone are free of titanium-containing compounds, and in a directesterification process, the entire melt phase reaction proceeds in theabsence of titanium-containing compounds, and most preferably, in anester exchange route, the entire melt phase reaction also proceeds inthe absence of titanium-containing compounds. In yet another embodiment,the only polycondensation catalyst added to the melt phase in a directesterification process is an antimony containing compound(s).

There is also provided a process for making a polyester polymer by meltphase polymerizing a melt in the presence of an antimony-containingcatalyst to produce a melt phase product, wherein the reaction time ofthe melt between an It.V. of 0.45 to an It.V. in the range of 0.70 dL/gto 0.90 dL/g is 100 minutes or less. Preferably, the pressure appliedwithin this range is about 2 mm Hg or less. Moreover, the melt phaseproduct produced by this process has a b* within a range of −5 to +5.

There is also provided polyester polymer having a degree ofcrystallinity of at least 25% and an It.V. of at least 0.70 dL/g withoutsolid state polymerizing the polymer, said polymer comprising antimonyresidues and having a b* color of −5 to +5 and an L* of at least 70. Thepolymer is desirably substantially free of titanium residues.

4. DETAILED DESCRIPTION OF THE INVENTION

The present invention may be understood more readily by reference to thefollowing detailed description of the invention.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise. For example,reference to processing or making a “polymer,” a “preform,” “article,”“container,” or “bottle” is intended to include the processing or makingof a plurality of polymers, preforms, articles, containers or bottles.References to a composition containing “an” ingredient or “a” polymer isintended to include other ingredients or other polymers, respectively,in addition to the one named.

By “comprising” or “containing” is meant that at least the namedcompound, element, particle, or method step etc. must be present in thecomposition or article or method, but does not exclude the presence ofother compounds, catalysts, materials, particles, method steps, etc.,even if the other such compounds, material, particles, method steps etc.have the same function as what is named, unless expressly excluded inthe claims.

It is also to be understood that the mention of one or more method stepsdoes not preclude the presence of additional method steps before orafter the combined recited steps or intervening method steps betweenthose steps expressly identified. Moreover, the lettering of processsteps is a convenient means for identifying discrete activities orsteps, and unless otherwise specified, recited process steps can bearranged in any sequence. Expressing a range includes all integers andfractions thereof within the range. Expressing a temperature or atemperature range in a process, or of a reaction mixture, or of a meltor applied to a melt, or of a polymer or applied to a polymer means inall cases that the reaction conditions are set to the specifiedtemperature or any temperature, continuously or intermittently, withinthe range; and that the reaction mixture, melt or polymer are subjectedto the specified temperature.

The intrinsic viscosity values described throughout this description areset forth in dL/g units as calculated from the inherent viscositymeasured at 25° C. in 60/40 wt/wt phenol/tetrachloroethane according tothe calculations immediately prior to Example 1 below.

Any compound or element added to the “melt phase” includes the additionof the compound or element as a feed at any point in the process and upto the stage when the melt is solidified, whether or not a melt actuallyexists at the addition point. Examples of addition points to a meltphase include to an esterification reactor, within a series aesterification reactors, to an oligomeric reaction mixture, beforepolycondensation and after conclusion of esterification, duringprepolymerization, or to the finisher.

A “base polyester polymer” is a polyester polymer obtained from the meltphase reaction and is made without the addition of bluing toners,without AA reducing additives, and without stabilizers. The basepolyester polymer, however, may be made with additives which reduce ametal catalyst compound to elemental metal.

A “melt phase product” is a polyester polymer obtained from a melt phasereaction made with or without the addition of bluing toners and othertoners, AA reducing additives, or reheat rate enhancing additives. Thepolyester polymer melt phase product may also contain stabilizers. Theadditives and toners may be added neat, in a carrier, or in aconcentrate to the melt phase. The melt phase products may be isolatedin the form of pellets or chips, or may be fed as a melt directly fromthe melt phase finishers into extruders and directed into molds formaking shaped articles such as bottle preforms (e.g. “melt to mold” or“melt to preform”). Unless otherwise specified, the melt phase productmay take any shape or form, including amorphous pellets, crystallizedpellets, solid stated pellets, preforms, sheets, bottles, and so forth.The molecular weight of the melt phase products may optionally beincreased in the solid state before melt extruding and shaping into anarticle.

A “polyester polymer composition” contains at least melt phase products,may optionally contain other ingredients one desires to add which arenot already contained in the melt phase products, and is considered thefully formulated composition which is used to make the shaped articles.For example, the bluing toners, AA reducing additives, or reheatadditives, if not already added to the melt phase for making the meltphase product, can be added to a melt phase product as a solid/solidblend or a melt blend, or the additives may be fed together with themelt phase products to an extruder for making shaped articles such thatthe polyester polymer composition is formed at or in the extruder. Theadditives and toners may be added neat, in a liquid carrier, or in asolid polyester concentrate.

The polyester polymer of this invention is any thermoplastic polyesterpolymer in any state (e.g. solid or molten), and in any shape, each asthe context in which the phrase is used dictates, and includes thecomposition of matter resulting from the melt phase, or as a solidstated polymer, or the composition of matter in a melt extrusion zone, abottle preform, or in a stretch blow molded bottle. The polyesterpolymer may optionally contain additives added to the polyester polymermelt phase product or to the solid stated pellet.

The term “melt” in the context of the melt phase reaction is a broadumbrella term referring to a stream undergoing reaction at any point inthe melt phase for making a polyester polymer, and includes the streamin the esterification phase even though the viscosity of the stream atthis stage is typically not measurable or meaningful, and also includesthe stream in the polycondensation phase including the prepolymer andfinishing phases, in-between each phase, and up to the point where themelt is solidified, and excludes a polyester polymer undergoing anincrease in molecular weight in the solid state.

L*, a*, and b* color ranges are described herein and in the appendedclaims. The L*, a*, or b* color are measured from specimens ground to apowder or made from a disc as explained below. A specimen is consideredto be within a specified L* or b* color range in the appended claims ifthe reported L* or b* value obtained from a specimen measured by any oneof these test methods is within the ranges expressed in the appendedclaims. For example, a b* color value outside a specified b* range asmeasured by one test method but inside a specified b* range as measuredby another test method is deemed to be a polymer within the specifiedrange because it satisfied the specified b* color range by one of thetest methods.

The polyester polymer composition is not so limited, e.g. thecomposition may be made with or without bluing toners, reheat additives,other catalysts, or any other additive. When specifying a color value,the polyester polymer composition having the color value does not haveto exhibit that value in all of its shapes or forms throughout itsproduction life from the melt phase to its manufacture into a bottle.Unless otherwise stated, a melt phase product or a polyester polymercomposition having a specified color value may apply to the polyesterpolymer composition in the form of a melt, a polyester polymer meltphase product, a bottle preform, and a blown bottle, each of which canbe subjected to any one of the test methods specified herein. The impactof the catalysts on the L*color of the melt phase product can be judgedusing the CIELab color standard L* values. The L* value is a measure ofbrightness. This value is measured in accordance with ASTM D 6290 foropaque or translucent powders (reflectance mode), and in accordance withASTM D 1746 for discs (transmission mode). Color measurement theory andpractice are discussed in greater detail in “Principles of ColorTechnology”, pp.25-66 by John Wiley & Sons, New York (1981) by Fred W.Billmeyer, Jr. Brightness is measured as L* in the CIE 1976opponent-color scale, with 100% representing a perfect white objectreflecting 100% at all wavelengths, or a colorless sample transmitting100% at all wavelengths. An L* of 100 in a colorless sample in thetransmittance mode would be perfectly transparent, while an L* of 0 in acolorless sample would be opaque.

The measurements of L*, a* and b* color values are conducted onspecimens prepared according to any one of the following methods. Coloris measured from polymer molded into discs (3 cm diameter with athickness of in a range of 66 to 68 mils). Alternatively, color valuesare measured on polyester polymers ground to a powder passing a 3 mmscreen.In the case of discs, a HunterLabUltraScan spectrophotometer isused to measure L*, a* and b* on three discs stacked together (in arange of approximately 198 to 204 mil thickness). A series of three,3-cm diameter, about 65-68 mil thick clear discs are prepared from thepolyester sample to be analyzed. Disc preparation is done by extrudingeach the polyester sample at a temperature of 278° C. and 120 rpm screwspeed into a micro-injector barrel at 283-285° C. The barrel should bepurged with material before attempting to mold any discs. The finaldiscs are prepared using an injector pressure of 100 psig to theinjection piston. The disc mold is maintained at a temperature range of10-20° C. by circulation of chilled water. Alternative extrusionequipment may be used provided that the samples are melted at thesetemperatures and extruded at the stated rate. The HunterLabUltraScanspectrophotometer is operated using a D65 illuminant light source with a10° observation angle and integrating sphere geometry. The colormeasurement is made in the total transmission (TTRAN) mode, in whichboth light transmitted directly through the sample and the light that isdiffusely scattered is measured. Three discs are stacked together usinga holder in front of the light source, with the area having the largestsurface area placed perpendicular to the light source.

For ground powders, the HunterLab UltraScan XE spectrophotometer isoperated using a D65 illuminant light source with a 10° observationangle and integrating sphere geometry. The HunterLab UltraScan XEspectrophotometer is zeroed, standardized, UV calibrated and verified incontrol. The color measurement is made in the reflectance (RSIN) mode.The polyester polymer specimens which are ground to a powder have aminimum degree of crystallinity of 15%. The powder should not beprepared from an amorphous polymer. Accordingly, it is expected thatcare should be taken when analyzing bottles from this method becausebottles have regions of lower crystallinity. In the event that it is notpossible to separate crystalline polymer from amorphous polymer, it isexpected that the disc method will be better suited to evaluate thecolor values.

Polymer crystallinity is determined using Differential ScanningCalorimetry (DSC). The sample weight for this measurement is 10±1 mg.The specimens subjected to analysis are preferably cryogenically ground.The first heating scan is performed. The sample is heated fromapproximately. 25° C. to 290° C. at a rate of 20° C./minute, and theabsolute value of the area of the melting endotherms (one or more) minusthe area of any crystallization exotherms is determined. This areacorresponds to the net heat of melting and is expressed in Joules. Theheat of melting of 100% crystalline PET is taken to be 119 Joules/gram,so the weight percent crystallinity of the pellet is calculated as thenet heat of melting divided by 119, and then multiplied by 100. Unlessotherwise stated, the initial melting point in each case is alsodetermined using the same DSC scan.

The percent crystallinity is calculated from both of:

Low peak melting point: T_(m1a)

High peak melting point: T_(m1b)

Note that in some cases, particularly at low crystallinity,rearrangement of crystals can occur so rapidly in the DSC instrumentthat the true, lower melting point is not detected. The lower meltingpoint can then be seen by increasing the temperature ramp rate of theDSC instrument and using smaller samples. A Perkin-Elmer Pyris-1calorimeter is used for high-speed calorimetry. The specimen mass isadjusted to be inversely proportional to the scan rate. About a 1 mgsample is used at 500° C./min and about 5 mg are used at 100° C./min.Typical DSC sample pans were used. Baseline subtraction is performed tominimize the curvature in the baseline.

Alternatively, percent crystallinity is also calculated from the averagegradient tube density of two to three pellets. Gradient tube densitytesting is performed according to ASTM D 1505, using lithium bromide inwater.

The following description relates to any one of the several embodimentsfor making melt phase products and the processes for making thepolyester polymer melt phase products. In the process for making apolyester polymer melt phase product, an antimony containing catalyst isadded to the melt phase, the melt containing the antimony catalyst ispolycondensed until the It.V. of the melt reaches at least 0.75 dL/g.Polyester polymer melt phase products in the form of pellets have anIt.V. of at least 0.75 dL/g and contain the residues of the antimonycatalyst. This It.V. is obtained without the necessity for solid statepolymerization. There is also provided a process for making shapedarticles from melt phase products by feeding to an extruder a polyesterpolymer composition comprising a melt phase products containing antimonyresidues and having an It.V. of at least 0.70 dL/g obtained withoutincreasing the molecular weight of the melt phase product by solid statepolymerization, melting the polyester polymer composition to produce amolten polyester polymer, and then extruding the molten polyesterpolymer composition through a die to form shaped articles.

In some additional embodiments, there is provided a melt phase processfor making a polyester polymer melt phase product containing at least100 ppm, and preferably up to about 500 ppm, or 450 ppm antimony basedon the weight of the product comprising adding an antimony-containingcatalyst to the melt phase; polycondensing a melt containing saidcatalyst in the melt phase; and before the It.V. of the melt reaches0.45 dL/g, continuously polycondensing the melt either at a temperaturewithin a range of 265° C. to 305° C. or at sub-atmospheric pressure or acombination thereof, in each case until the It.V. of the melt reaches atleast 0.75 dL/g; to produce said polyester polymer melt phase producthaving a b* color in the range of −5 to +5.

Also as noted above, there is provided a melt phase process for making apolyester polymer melt phase product comprising:

a) esterifying or transesterifying a diol and a carboxylic acidcomponent comprising dicarboxylic acids, dicarboxylic acid derivatives,and mixtures thereof to produce an oligomeric mixture;

b) polycondensing the oligomeric mixture to produce a polyester polymermelt having an It.V. of at least 0.75 dL/g; and

c) adding an antimony compound to the melt phase before the It.V. of thepolyester polymer melt reaches 0.45 dL/g; and

d) optionally adding a stabilizer to the melt phase;

wherein the polyester polymer melt phase product has a b* color of −5 to+5.

Each of these embodiments is now described in more detail.

Examples of suitable polyester polymers made by the process includepolyalkylene terephthalate homopolymers and copolymers modified with oneor more modifiers in an amount of 40 mole % or less, preferably lessthan 15 mole %, most preferably less than 10 mole % (collectivelyreferred to for brevity as “PAT”) and polyalkylene naphthalatehomopolymers and copolymers modified with less than 40 mole %,preferably less than 15 mole %, most preferably less than 10 mole %, ofone or more modifiers (collectively referred to herein as “PAN”), andblends of PAT and PAN. Unless otherwise specified, a polymer includesboth its homopolymer and copolymer variants. The preferred polyesterpolymer is a polyalkylene terephthalate polymer, and most preferred ispolyethylene terephthalate polymer.

Typically, polyesters such as polyethylene terephthalate are made byreacting a diol such as ethylene glycol with a dicarboxylic acid as thefree acid or its dimethyl ester to produce an ester monomer and/oroligomers, which are then polycondensed to produce the polyester. Morethan one compound containing carboxylic acid group(s) or derivative(s)thereof can be reacted during the process. All the compounds containingcarboxylic acid group(s) or derivative(s) thereof that are in theproduct comprise the “carboxylic acid component.” The mole % of all thecompounds containing carboxylic acid group(s) or derivative(s) thereofthat are in the product add up to 100. The “residues” of compound(s)containing carboxylic acid group(s) or derivative(s) thereof that are inthe product refers to the portion of said compound(s) which remains inthe oligomer and/or polymer chain after the condensation reaction with acompound(s) containing hydroxyl group(s). The residues of the carboxylicacid component refers to the portion of the said component which remainsin the oligomer and/or polymer chain after the said component iscondensed with a compound containing hydroxyl group(s).

More than one compound containing hydroxyl group(s) or derivativesthereof can become part of the polyester polymer product(s). All thecompounds containing hydroxyl group(s) or derivatives thereof thatbecome part of said product(s) comprise the hydroxyl component. The mole% of all the compounds containing hydroxyl group(s) or derivativesthereof that become part of said product(s) add up to 100. The residuesof compound(s) containing hydroxyl group(s) or derivatives thereof thatbecome part of said product refers to the portion of said compound(s)which remains in said product after said compound(s) is condensed with acompound(s) containing carboxylic acid group(s) or derivative(s) thereofand further polycondensed with polyester polymer chains of varyinglength. The residues of the hydroxyl component refers to the portion ofthe said component which remains in said product.

The mole % of the hydroxyl residues and carboxylic acid residues in theproduct(s) can be determined by proton NMR.

In one embodiment, the polyester polymers comprise:

-   -   (a) a carboxylic acid component comprising at least 80 mole %,        or at least 90 mole %, or at least 92 mole %, or at least 96        mole %, of the residues of terephthalic acid, derivates of        terephthalic acid, naphthalene-2,6-dicarboxylic acid,        derivatives of naphthalene-2,6-dicarboxylic acid, or mixtures        thereof, and    -   (b) a hydroxyl component comprising at least 80 mole %, or at        least 90 mole %, or at least 92 mole %,. or at least 96 mole %,        of the residues of ethylene glycol,        based on 100 mole percent of carboxylic acid component residues        and 100 mole percent of hydroxyl component residues in the        polyester polymer. Preferred are the residues of terephthalic        acid and their derivates.

The reaction of the carboxylic acid component with the hydroxylcomponent during the preparation of the polyester polymer is notrestricted to the stated mole percentages since one may utilize a largeexcess of the hydroxyl component if desired, e.g. on the order of up to200 mole % relative to the 100 mole % of carboxylic acid component used.The polyester polymer made by the reaction will, however, contain thestated amounts of aromatic dicarboxylic acid residues and ethyleneglycol residues.

Derivates of terephthalic acid and naphthalane dicarboxylic acid includeC₁-C₄ dialkylterephthalates and C₁-C₄ dialkylnaphthalates, such asdimethylterephthalate and dimethylnaphthalate

In addition to a diacid component of terephthalic acid, derivates ofterephthalic acid, naphthalene-2,6-dicarboxylic acid, derivatives ofnaphthalene-2,6-dicarboxylic acid, or mixtures thereof, the carboxylicacid component(s) of the present polyester may include one or moreadditional modifier carboxylic acid compounds. Such additional modifiercarboxylic acid compounds include mono-carboxylic acid compounds,dicarboxylic acid compounds, and compounds with a higher number ofcarboxylic acid groups. Examples include aromatic dicarboxylic acidspreferably having 8 to 14 carbon atoms, aliphatic dicarboxylic acidspreferably having 4 to 12 carbon atoms, or cycloaliphatic dicarboxylicacids preferably having 8 to 12 carbon atoms. More specific examples ofmodifier dicarboxylic acids useful as an acid component(s) are phthalicacid, isophthalic acid, naphthalene-2,6-dicarboxylic acid,cyclohexanedicarboxylic acid, cyclohexanediacetic acid,diphenyl-4,4′-dicarboxylic acid, succinic acid, glutaric acid, adipicacid, azelaic acid, sebacic acid, and the like, with isophthalic acid,naphthalene-2,6-dicarboxylic acid, and cyclohexanedicarboxylic acidbeing most preferable. It should be understood that use of thecorresponding acid anhydrides, esters, and acid chlorides of these acidsis included in the term “carboxylic acid”. It is also possible fortricarboxyl compounds and compounds with a higher number of carboxylicacid groups to modify the polyester.

In addition to a hydroxyl component comprising ethylene glycol, thehydroxyl component of the present polyester may include additionalmodifier mono-ols, diols, or compounds with a higher number of hydroxylgroups. Examples of modifier hydroxyl compounds include cycloaliphaticdiols preferably having 6 to 20 carbon atoms and/or aliphatic diolspreferably having 3 to 20 carbon atoms. More specific examples of suchdiols include diethylene glycol; triethylene glycol;1,4-cyclohexanedimethanol; propane-1,3-diol; butane-1,4-diol;pentane-1,5-diol; hexane-1,6-diol; 3-methylpentanediol-(2,4);2-methylpentanediol-(1,4); 2,2,4-trimethylpentane-diol-(1,3);2,5-diethylhexanediol-(1,3); 2,2-diethyl propane-diol-(1,3);hexanediol-(1,3); 1,4-di-(hydroxyethoxy)-benzene;2,2-bis-(4-hydroxycyclohexyl)-propane;2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane;2,2-bis-(3-hydroxyethoxyphenyl)-propane; and2,2-bis-(4-hydroxypropoxyphenyl)-propane.

The particular process for making the polyester polymer melt phaseproduct from the melt is not limited. Polyester melt phase manufacturingprocesses typically include a) direct condensation of a dicarboxylicacid with the diol, optionally in the presence of esterificationcatalysts, in the esterification zone, followed by b) polycondensationin the prepolymer and finishing phases in the presence of apolycondensation catalyst; or a) ester exchange usually in the presenceof a transesterification catalyst in the ester exchange phase, followedby b)polycondensation in the prepolymer and finishing phases in thepresence of a polycondensation catalyst.

To further illustrate, in step a), a mixture of one or more dicarboxylicacids, preferably aromatic dicarboxylic acids, or ester formingderivatives thereof, and one or more diols are continuously fed to anesterification reactor operated at a temperature of between about 200°C. and 300° C., and at a super-atmospheric pressure of between about 1psig up to about 70 psig. The residence time of the reactants typicallyranges from between about one and five hours. Normally, the dicarboxylicacid is directly esterified with diol(s) at elevated pressure and at atemperature of about 240° C. to about 285° C.

The esterification reaction is continued until a degree ofesterification of at least 70% is achieved, but more typically until adegree of esterification of at least 85% is achieved to make the desiredoligomeric mixture (or otherwise also known as the “monomer”). Thereaction to make the oligomeric mixture is typically uncatalyzed in thedirect esterification process and catalyzed in ester exchange processes.The antimony containing catalyst may optionally be added in theesterification zone along with raw materials. Typical ester exchangecatalysts which may be used in an ester exchange reaction betweendialkylterephthalate and a diol include titanium alkoxides and dibutyltin dilaurate, zinc compounds, manganese compounds, each used singly orin combination with each other. Any other catalyst materials well knownto those skilled in the art are suitable. In a most preferredembodiment, however, the ester exchange reaction proceeds in the absenceof titanium compounds. Titanium based catalysts present during thepolycondensation reaction negatively impact the b* by making the meltmore yellow. While it is possible to deactivate the titanium basedcatalyst with a stabilizer after completing the ester exchange reactionand prior to commencing polycondensation, in a most preferred embodimentit is desirable to eliminate the potential for the negative influence ofthe titanium based catalyst on the b* color of the melt by conductingthe direct esterification or ester exchange reactions in the absence ofany titanium containing compounds. Suitable alternative ester exchangecatalysts include zinc compounds, manganese compounds, or mixturesthereof.

The resulting oligomeric mixture formed in the esterification zone(which includes direct esterification and ester exchange processes)includes bis(2-hydroxyethyl)terephthalate (BHET) monomer, low molecularweight oligomers, DEG, and trace amounts of water as the condensationby-product not removed in the esterification zone, along with othertrace impurities from the raw materials and/or possibly formed bycatalyzed side reactions, and other optionally added compounds such astoners and stabilizers. The relative amounts of BHET and oligomericspecies will vary depending on whether the process is a directesterification process in which case the amount of oligomeric speciesare significant and even present as the major species, or a esterexchange process in which case the relative quantity of BHETpredominates over the oligomeric species. Water is removed as theesterification reaction proceeds to drive the equilibrium toward thedesired products. The esterification zone typically produces the monomerand oligomer species, if any, continuously in a series of one or morereactors. Alternately, the monomer and oligomer species in theoligomeric mixture could be produced in one or more batch reactors. Itis understood, however, that in a process for making PEN, the reactionmixture will contain the monomeric species bis 2,6-(2-hydroxyethyl)naphthalate and its corresponding oligomers. At this stage, the It.V. isusually not measurable or is less than 0.1. The average degree ofpolymerization of the molten oligomeric mixture is typically less than15, and often less than 7.0.

Once the oligomeric mixture is made to the desired degree ofesterification, it is transported from the esterification zone orreactors to the polycondensation zone in step b). The polycondensationzone is typically comprised of a prepolymer zone and a finishing zone,although it is not necessary to have split zones within apolycondensation zone. Polycondensation reactions are initiated andcontinued in the melt phase in a prepolymerization zone and finished inthe melt phase in a finishing zone, after which the melt is solidifiedto form the polyester polymer melt phase product, generally in the formof chips, pellets, or any other shape.

Each zone may comprise a series of one or more distinct reaction vesselsoperating at different conditions, or the zones may be combined into onereaction vessel using one or more sub-stages operating at differentconditions in a single reactor. That is, the prepolymer stage caninvolve the use of one or more reactors operated continuously, one ormore batch reactors, or even one or more reaction steps or sub-stagesperformed in a single reactor vessel. The residence time of the melt inthe finishing zone relative to the residence time of the melt in theprepolymerization zone is not limited. For example, in some reactordesigns, the prepolymerization zone represents the first half ofpolycondensation in terms of reaction time, while the finishing zonerepresents the second half of polycondensation. Other reactor designsmay adjust the residence time between the finishing zone to theprepolymerization zone at about a 1.5:1 ratio or higher. A commondistinction between the prepolymerization zone and the finishing zone inmany designs is that the latter zone frequently operates at a highertemperature and/or lower pressure than the operating conditions in theprepolymerization zone. Generally, each of the prepolymerization and thefinishing zones comprise one or a series of more than one reactionvessel, and the prepolymerization and finishing reactors are sequencedin a series as part of a continuous process for the manufacture of thepolyester polymer.

In the prepolymerization zone, also known in the industry as the lowpolymerizer, the low molecular weight monomers and oligomers in theoligomeric mixture are polymerized via polycondensation to formpolyethylene terephthalate polyester (or PEN polyester) in the presenceof an antimony containing catalyst added to the melt phase described asstep c) in the esterification or polycondensation zones, such asimmediately prior to initiating polycondensation, duringpolycondensation, or to the esterification zone prior to initiatingesterification or ester exchange or during or upon completion of theesterification or ester exchange reaction. If the antimony catalyst isnot added in the monomer esterification stage for the manufacture of theoligomeric mixture, it is added at this stage to catalyze the reactionbetween the monomers and between the low molecular weight oligomers andbetween each other to build molecular weight and split off the diol(s)as a by-product. If the antimony containing catalyst is added to theesterification zone, it is typically blended with the diol(s) and fedinto the esterification reactor.

If desired, the antimony containing catalyst is added to the melt phasebefore the It.V. of the melt exceeds 0.30 dL/g. By adding the antimonycontaining catalyst before the It.V. of the melt exceeds 0.30 dL/g,inordinately long reaction times are avoided. The antimony containingcatalyst can be added to the esterification zone or the polycondensationzone or both. Preferably, the antimony containing catalyst is addedbefore the It.V. of the melt exceeds 0.2 dL/g, or regardless of theactual It.V., more preferably before entering the polycondensation zone.The commencement of the polycondensation reaction is generally marked byeither a higher actual operating temperature than the operatingtemperature in the esterification zone, or a marked reduction inpressure compared to the esterification zone, or both. In some cases,the polycondensation zone is marked by higher actual operatingtemperatures and lower (usually sub-atmospheric) pressures than theactual operating temperature and pressure in the esterification zone.

Suitable antimony containing catalysts added to the melt phase are anyantimony containing catalysts effective to catalyze the polycondensationreaction. These include, but are not limited to, antimony (III) andantimony (V) compounds recognized in the art and in particular,diol-soluble antimony (III) and antimony (V) compounds, with antimony(III) being most commonly used. Other suitable compounds include thoseantimony compounds that react with, but are not necessarily soluble inthe diols prior to reaction, with examples of such compounds includingantimony (III) oxide. Specific examples of suitable antimony catalystsinclude antimony (III) oxide and antimony (III) acetate, antimony (III)glycolates, antimony (III) ethylene glycoxide and mixtures thereof, withantimony (III) oxide being preferred. The preferred amount of antimonycatalyst added is that effective to provide a level of between about atleast 100, or at least 180, or at least 200 ppm. The stated amount ofantimony is based on the metal content, regardless of its oxidationstate. For practical purposes, not more than about 500 ppm of antimonyby weight of the resulting polyester is needed.

The prepolymer polycondensation stage generally employs a series of oneor more vessels and is operated at a temperature of between about 230°C. and 305° C. for a period between about five minutes to four hours.During this stage, the It.V. of the monomers and oligomers are increasedgenerally up to about no more than 0.45 dL/g. The diol byproduct isremoved from the prepolymer melt generally using an applied vacuumranging from 4 to 200 torr to drive the polycondensation of the melt. Inthis regard, the polymer melt is sometimes agitated to promote theescape of the diol from the polymer melt. As the polymer melt is fedinto successive vessels, the molecular weight and thus the intrinsicviscosity of the polymer melt increases. The pressure of each vessel isgenerally decreased to allow for a greater degree of polymerization ineach successive vessel or in each successive zone within a vessel. Tofacilitate removal of glycols, water, alcohols, aldehydes, and otherreaction products, the reactors are typically run under a vacuum orpurged with an inert gas. Inert gas is any gas which does not causeunwanted reaction or product characteristics at reaction conditions.Suitable gases include, but are not limited to argon, helium andnitrogen.

Once the desired It.V. in the prepolymerization zone is obtained,generally no greater than 0.45, the prepolymer is fed from theprepolymer zone to a finishing zone where the second stage ofpolycondensation is continued in one or more finishing vesselsgenerally, but not necessarily, ramped up to higher temperatures thanpresent in the prepolymerization zone, to a value within a range of from250° C. to 310° C., more generally from 270 to 300° C., until the It.V.of the melt is increased from the It.V of the melt in theprepolymerization zone (typically 0.30 but usually not more than 0.45)to an It.V in the range of from about at least 0.70, or at least 0.75dL/g, to about 1.2 dL/g. The final vessel, generally known in theindustry as the “high polymerizer,” “finisher,” or “polycondenser,” isalso usually operated at a pressure lower than used in theprepolymerization zone to further drive off the diol and increase themolecular weight of the polymer melt. The pressure in the finishing zonemay be within the range of about 0.2 and 20 torr, or 0.2 to 10 torr, or0.2 to 2 torr. Although the finishing zone typically involves the samebasic chemistry as the prepolymer zone, the fact that the size of themolecules, and thus the viscosity differs, means that the reactionconditions also differ. However, like the prepolymer reactor, each ofthe finishing vessel(s) is operated under vacuum or inert gas, and eachis typically agitated to facilitate the removal of the diol and water.

With the process of the invention, the melt phase polycondensationreaction is capable of proceeding within a wide range of operatingtemperatures and catalyst concentrations while maintaining an acceptableb* color of the base polyester polymer below +5. Thus, the process ofthe invention is not restricted to low catalyst concentrations and lowpolycondensation temperatures to maintain an acceptable b* color.

It is to be understood that the process described above is illustrativeof a melt phase process, and that the invention is not limited to thisillustrative process. For example, while reference has been made to avariety of operating conditions at certain discrete It.V. values,differing process conditions may be implemented inside or outside of thestated It.V. values, or the stated operating conditions may be appliedat It.V. points in the melt other than as stated. Moreover, one mayadjust the the process conditions based on reaction time instead ofmeasuring the It.V. of the melt. Moreover, the process is not limited tothe use of tank reactors in series or parallel or to the use ofdifferent vessels for each zone. Moreover, it is not necessary to usesplit the polycondensation reaction into a prepolymer zone and afinishing zone because the polycondensation reaction can take place on acontinuum of slight variations in operating conditions over time in onepolycondensation reactor or in a multitude of reactors in series, eitherin a batch, semi-batch, or a continuous process.

Once the desired It.V. is obtained with a minimum It.V. of 0.70 dL/g, ora minimum It.V. of 0.75 dL/g in other embodiments, the polyester polymermelt in the melt phase reactors is discharged as a melt phase product.The melt phase product is further processed to a desired form, such asan amorphous pellet, or a shaped article via a melt to mold process. TheIt.V. of the melt phase product is at least 0.70 dL/g, or 0.75 dL/g, or0.78 dL/g, or 0.80 dL/g, and up to about 1.2 dL/g, or 1.15 dL/g.

There is also provided a process for making a melt phase product bypolymerizing a melt in the presence of an antimony-containing catalyst,wherein the reaction time of the melt from an It.V. of 0.45 dL/g throughand up to an It.V. in the range of 0.70 dL/g to 0.90 dL/g, or throughand up to completing the polycondensation reaction, is 100 minutes orless, or 80 minutes or less, or 70 minutes or less. In anotherembodiment, the reaction time of the melt from an It.V. of 0.3 dL/gthrough and up to an It.V. in the range of 0.70 dL/g to 0.90 dL/g is 100minutes or less, or 80 minutes or less, or 70 minutes or less.Alternatively, the reaction time in the finishing zone to complete thepolycondensation is 100 minutes or less, or 80 minutes or less,regardless of the It.V. of the melt fed to the finishing zone.Preferably, the pressure applied within this range is about 2 mm Hg orless, and about 0.05 mm Hg or more. Moreover, the b* color of the meltphase product produced by this process is within the range of −5 to +5.The process of the invention permits one to rapidly make a basepolyester polymer having an acceptable b* color.

There is also provided an embodiment comprising feeding to an extruder,such as an injection molding machine, a a polyester polymer compositioncomprising a melt phase product containing antimony residues and havingan It.V. of at least 0.70 dL/g obtained without increasing the molecularweight of the melt phase product in the solid state, melting thepolyester polymer composition to produce a molten polyester polymer,extruding the molten polyester polymer composition through a die to formshaped articles, wherein the shaped articles have a b* color rangingfrom −5 to +5. By making the high It.V. product in the melt phase, thesolid stating step can be altogether avoided. Solid stating is commonlyused for increasing the molecular weight (and the It.V) of the pelletsin the solid state, usually by at least 0.05 It.V. units, and moretypically from 0.1 to 0.5 It.V. units.

While the production of the polyester polymer melt phase product havinga high It.V. of at least 0.75 dL/g avoids the need for solid stating, inan optional embodiment, the melt phase products may be solid stated ifdesired to further increase their molecular weight.

In yet another embodiment, there is also provided a polyester polymercomposition comprising melt phase products having a degree ofcrystallinity of at least 25%, an It.V. of at least 0.70 dL/g withoutsolid state polymerization, and antimony containing residues, saidpolyester polymer composition having a b* color of −5 to +5, and an L*of at least 70. The degree of crystallinity is measured by the techniquedescribed above. The degree of crystallinity is optionally at least 30%,or at least 35%, or at least 40%. The melt phase products are preferablysubstantially free of titanium residues, and in a direct esterificationprocess, are preferably prepared by adding to the melt phase apolycondensation catalyst consisting only of antimony containingcompound(s). Thus, polyester polymers made rapidly in the melt phasehaving acceptable color can now be isolated as bright, crystallizedpellets and provided to a converter without the need for increasingtheir molecular weight in the solid state.

In yet another embodiment, there is also provided a polyester polymercomposition substantially free of titanium residues comprising apolyester polymer having a b* color of −5 to +5 CIELAB units, an L* ofat least 70 CIELAB units, and an It.V. of at least 0.75 dL/g obtainedwithout subjecting the polymer to an increase in its molecular weightthrough solid stating, and containing antimony residues. Thesecompositions may contain at least 4 ppm of a reheat additive, astabilizer, a bluing toner, and/or acetaldehyde scavenging additive.

If desired, the thermal stability of the polyester polymer can beincreased and the tendency of the molded article to form haze can bedecreased by adding a suitable stabilizer to the melt described as stepd). Not every formulation requires the addition of a stabilizer, and notevery end use application requires exceptionally high brightness.Suitable stabilizer compounds, if used, contain one or more phosphorusatoms.

The phosphorus containing stabilizer compounds may be added at any pointin the melt phase process. For example, the catalyst stabilizer can beadded at any point in the melt phase process, including as a feed to theesterification zone, during esterification, to the oligomeric mixture,to the beginning of polycondensation, and during or afterpolycondensation. The stabilizer is desirably added after the additionof the antimony containing catalyst and before pelletization, such asbefore the prepolymer zone, to the prepolymer zone, to the finisher, orbetween the finishing zone and a pelletizer.

In an ester exchange reaction, the catalyst stabilizer or othercompounds effective for deactivating ester exchange catalysts can beadditionally be added at the conclusion of the ester exchange reactionand before polycondensation in molar amounts sufficient to deactivatethe ester exchange catalyst without significantly impairing thecatalytic activity of the antimony containing catalyst added afterdeactivating the ester exchange catalyst. However, the ester exchangecatalyst does not have to deactivated prior to adding the antimonycontaining catalyst if the ester exchange catalyst does not undulyimpair the color of the resulting polyester polymer melt phase product.Titanium containing catalysts, however, have to be deactivated beforethe start of polycondensation, and preferably are not added to the esterexchange zone, esterification zone or polycondensation zones at allsince they have been found to unduly impair the b* color. In the case ofdirect esterification, and in the absence of any titanium-containingcompounds, stabilizers, if added, can be added after the desired It.V.is obtained.

Specific examples of stabilizers include acidic phosphorus compoundssuch as phosphoric acid, phosphorous acid, polyphosphoric acid,carboxyphosphonic acids, phosphonic acid derivatives, and each of theiracidic salts and acidic esters and derivatives, including acidicphosphate esters such as phosphate mono- and di-esters and non acidicphosphate esters (e.g. phosphate tri-esters) such as trimethylphosphate, triethyl phosphate, tributyl phosphate, tributoxyethylphosphate, tris(2- ethylhexyl) phosphate, oligomeric phosphatetri-esters, trioctyl phosphate, triphenyl phosphate, tritolyl phosphate,(tris)ethylene glycol phosphate, triethyl phosphonoacetate, dimethylmethyl phosphonate, tetraisopropyl methylenediphosphonate, mixtures ofmono-, di-, and tri-esters of phosphoric acid with ethylene glycol,diethylene glycol, and 2-ethylhexanol, or mixtures of each. Otherexamples include distearylpentaerythritol diphosphite, mono-, di-, andtrihydrogen phosphate compounds, phosphite compounds, certain inorganicphosphorus compounds such as monosodium phosphate, zinc or calciumphosphates, poly(ethylene)hydrogen phosphate, silyl phosphates;phosphorus compounds used in combinations with hydroxy- oramino-substituted carboxylic acids such as methyl salicylate, maleicacid, glycine, or dibutyl tartrate; each useful for inactivating metalcatalyst residues.

The quantity of phosphorus relative to the antimony atoms used in thisprocess is not limited, but consideration is taken for the amount ofantimony metal and other metals present in the melt. The molar ratio ofphosphorus to antimony is desirably at least 0.025:1, or in the range of0.025:1 to 5.0:1, preferably about 0.1:1 to 3.0:1.

To the melt or to the melt phase products may also be added anacetaldehyde bonding or scavenging compound. The particular point ofaddition will depend somewhat on the type of AA loweringcompound used.The AA scavenging compound may be fed to an extruder used as part of themelt processing of pellets into preforms or other shaped articles, orthe AA scavenging compound may be added to the melt in the melt phaseprocess. Some scavengers have a finite number of reaction sites. If AAscavengers are added to the melt-phase, often all the reactive siteshave been used up by the time the polyester polymer pellets are meltedto make preforms. Other AA scavengers are not stable at the temperaturesand times involved in polycondensation. If the AA scavenging agentcontains sufficient reaction sites and the material and its product arethermally stable, they may be added to the melt in the melt phaseprocess for making the polyester polymer, such as in the finishingsection where the It.V. will exceed 0.45 dL/g, and more preferably afterthe finishing section and before pelletization where the It.V. willexceed 0.70 dL/g.

The addition of AA scavenging additives is optional and not everyapplication requires the presence of this additive. However, if used,the AA scavenging additive is generally added in an amount between about0.05 and 5 weight %, more preferably between about 0.1 and 3 weight %based on the weight of the polyester polymer melt phase product. Itshould be understood that the additive may be added individually or in aliquid carrier or as a solid concentrate in a compatible polymer baseresin. The AA scavenging additive may be present in a concentrate in anamount ranging from 0.5 wt.% to 40 wt.% and let down into a bulkpolyester polymer melt at the injection molding machine or to the meltin the melt phase process for making the polyester polymer, such as inthe finishing section where the It.V. will exceed 0.45 dL/g and morepreferably after the finishing section where the It.V. will exceed 0.70dL/g.

The AA scavenging additive may be any additive known to react with AA.Suitable additives include polyamides such as those disclosed in U.S.Pat. Nos. 5,266,413, 5,258,233 and 4,8837,115; polyesteramides such asthose disclosed in U.S. application Ser. No. 595,460, filed Feb. 5,1996; nylon-6 and other aliphatic polyamides such as those disclosed inJapan Patent Application Sho 62-182065 (1987);ethylenediaminetetraacetic acid (U.S. Pat. No. 4,357,461), alkoxylatedpolyols (U.S. Pat. No. 5,250,333), bis(4-[bgr]-hydroxyethoxyphenyl)sulfone (U.S. Pat. No. 4,330,661), zeolite compounds (U.S. Pat. No.5,104,965), 5-hydroxyisophthalic acid (U.S. Pat. No. 4, 093,593),supercritical carbon dioxide (U.S. Pat. Nos. 5,049,647 and 4,764,323)and protonic acid catalysts (U.S. Pat. Nos. 4,447,595 and 4,424, 337).Preferably the AA lowering additive is selected from polyamides andpolyesteramides. Suitable polyamides include homo and copolyamides suchas poly(caprolactam), poly(hexamethylene-adipamide),poly(m-xylylene-adipamide), etc. Branched or hyperbranched polyamidescan also be used.

Suitable poyesteramides include the polyesteramides prepared fromterephthalic acid, 1,4-cyclohexane-dimethanol, isophthalic acid andhexamethylene diamine (preferably with about 50:50 ratio of the diacidsto the diamine and a 50:50 ratio of the glycol to the diamine); thepolyesteramide prepared from terephthalic acid,1,4-cyclohexanedimethanol, adipic acid and hexamethylene diamine; thepolyesteramides prepared from terephthalic acid,1,4-cylcohexanedimethanol and bis(p-amino-cylcohexyl)methane. Otherknown scavengers such as polyethyleneimine may also be used.

Preferred AA reducing agents are polyamide polymers selected from thegroup consisting of low molecular weight partially aromatic polyamideshaving a number average molecular weight of less than 15,000, lowmolecular weight aliphatic polyamides having a number average molecularweight of less than 7,000, and combinations thereof. Specific polymerswithin these preferred molecular weight ranges include poly(m-xylyleneadipamide), poly(hexamethylene isophthalamide), poly(hexamethyleneadipamide-co-isophthalamide), poly(hexamethyleneadipamide-co-terephthalamide), and poly(hexamethyleneisophthalamide-co-terephthalamide), poly(hexamethylene adipamide) andpoly(caprolactam).

Other AA reducing agents include anthranilamides such as2-aminobenzamide or the like as mentioned in U.S. Pat. No. 6,274,212,incorporated herein by reference. Any conventional AA reducing agent maybe used.

In addition, certain agents which colorize the polymer can be added tothe melt. In one embodiment, a bluing toner is added to the melt inorder to reduce the b* of the resulting polyester polymer melt phaseproduct. Such bluing agents include blue inorganic and organic toners.In addition, red toners can also be used to adjust the a* color. Organictoners, e.g., blue and red organic toners, such as those tonersdescribed in U.S. Pat. Nos. 5,372,864 and 5,384,377, which areincorporated by reference in their entirety, can be used. The organictoners can be fed as a premix composition. The premix composition may bea neat blend of the red and blue compounds or the composition may bepre-dissolved or slurried in one of the polyester's monomeric species,e.g., ethylene glycol.

Alternatively, or in addition to, inorganic bluing agents can also beadded to the melt to reduce its yellow hue. Cobalt (II) compounds, suchas cobalt (II) carboxylates, are one of the most widely used toners inthe industry to mask the yellow color of polymers. When directesterification is not being used, the cobalt carboxylate can be added tothe ester exchange reactor to also act as an ester exchange catalyst.

The total amount of toner components added depends, of course, on theamount of inherent yellow color in the base polyester and the efficacyof the toner. Generally, a concentration of up to about 15 ppm ofcombined organic toner components and a minimum concentration of about0.5 ppm are used. The total amount of bluing additive typically rangesfrom 0.5 to 10 ppm.

The toners can be added to the esterification zone or to thepolycondensation zone. Preferably, the toners are added toesterification zone or to the early stages of the polycondensation zone,such as to a prepolymerization reactor.

The process of the invention has the advantage of producing a basepolyester polymer melt phase product having both a high It.V. and a lowb* rating. The b* color of the polyester polymer melt phase product iswithin the range of −5 to +5 CIELAB units, preferably between −5 and 4,or between −5 and 3. These values are obtainable by the process of theinvention with and without the presence of bluing toners added in themelt phase or added to the product. When the base polyester polymer hasa low b* rating, a bluing toner is either not required or a smallerconcentration of bluing toners is needed to drive the color of thepolyester polymer melt phase product closer to a neutral b* of 0.Depending on the nature of the bluing toner and other ingredients in thepolyester polymer composition, the addition of less bluing toner has afurther advantage of minimizing the impact on the L* brightness of thepolyester polymer. While toners are optional and can be added to themelt if desired, by using an antimony-containing catalyst to catalyzethe polycondensation reaction, the base polyester polymer has thecapability of remaining within a b* rating of −5 to +5 without the needto add toners.

Accordingly, in another embodiment, the high It.V. polyester polymermelt phase product and the polyester polymer compositions of theinvention have a b* color between −5 to +5 CIELAB units without theaddition of bluing toners. In an alternative embodiment, the high It.V.polyester polymer melt phase product, and the polyester polymercompositions, of the invention not only have a b* color between −5 to +5CIELAB units, but also have a L* brightness value of 70 CIELAB units ormore, or 74 or more, or 76 or more, with and without the presence ofbluing toners or residues thereof or reheat additives. In carbonatedsoft drink bottle applications, the melt phase product may containbluing toners and an additive to reduce the antimony compound to form Sbmetal in situ to aid the reheat rate.

Since coloring agents may be added if desired, there are also providedembodiments wherein the polyester polymer melt phase product has anIt.V. of at least 0.75 dL/g, a b* color between −5 to +5 CIELAB units,an L* brightness value of 70 CIELAB units or more, and contains a bluingtoner or residue thereof. In a further embodiment, there is provided apolyester polymer composition comprising a melt phase product made inthe melt phase to an It.V. of at least 0.70 dL/g, a bluing toner orresidue thereof and/or a red toner or residue thereof, and a reheatadditive, wherein the composition has a b* color between −5 to +5 CIELABunits and a L* brightness value of 70 CIELAB units or more, morepreferably 74 CIELAB units or more. In a preferred aspect to both ofthese embodiments, the bluing toner is an organic toner, and thepolyester polymer composition is devoid of cobalt compounds added to theesterification reactor. Minor amounts of certain cobalt compounds may bepresent with the diacid and/or diol starting materials. Although cobaltcompounds mask the yellow color of some polyester polymers, they alsomay, impart a gray color to the polymer at high levels and/or lower theresulting polymer's thermal stability in PET polymers if insufficientamounts of phosphorus compounds are present to bind to cobalt.

For processes conducted entirely in the melt-phase, high It.V. polyesterpolymer melt phase products catalyzed with antimony compounds tend to bedarker than high It.V. titanium compound catalyzed polyester polymerswithout the addition of any reheat additive, toners, or AA loweringadditives. However, some of the antimony in the Sb⁺³ oxidation state maybe reduced to the Sb⁰ oxidation state merely at reaction temperaturesand times without the presence of added reducing compounds. The Sb⁰metal present in the polymer has the advantage of also acting as areheat aid to increase the rate at which bottle preforms reheat prior toblow molding. A reducing compound can be added to the polycondensationreaction to produce even more Sb⁰ in situ. Examples of reducingcompounds include phosphorous acid, alkyl or aryl phosphonic acids, andalkyl or aryl phosphites. Reduced antimony often delivers equivalentreheat increases with less reduction in the brightness of the polymerthan is the case for other added reheat additives such as black ironoxide and carbon black.

Examples of other reheat additives (a reheat additive is deemed acompound added to the melt in contrast to forming a reheat aid in situ)used in combination with reduced antimony formed in situ or as analternative to reduced antimony formed in situ include activated carbon,carbon black, antimony metal, tin, copper, silver, gold, palladium,platinum, black iron oxide, and the like, as well as near infraredabsorbing dyes, including, but not limited to those disclosed in U.S.Pat. No. 6,197,851 which is incorporated herein by reference.

The iron oxide, which is preferably black, is used in very finelydivided form, e.g., from about 0.01 to about 200 μm, preferably fromabout 0.1 to about 10.0 μm, and most preferably from about 0.2 to about5.0 μm. Suitable forms of black iron oxide include, but are not limitedto magnetite and maghemite. Red iron oxide may also be used. Such oxidesare described, for example, on pages 323-349 of Pigment Handbook, Vol.1, copyright 1973, John Wiley & Sons, Inc.

Other components can be added to the composition of the presentinvention to enhance the performance properties of the polyesterpolymer. For example, crystallization aids, impact modifiers, surfacelubricants, denesting agents, antioxidants, ultraviolet light absorbingagents, metal stabilizers, colorants, nucleating agents, acetaldehydebonding compounds, other reheat rate enhancing aids, sticky bottleadditives such as talc, and fillers and the like can be included.

The compositions of the present invention optionally may additionallycontain one or more UV absorbing compounds. One example includes UVabsorbing compounds which are covalently bound to the polyester moleculeas either a comonomer, a side group, or an end group. Suitable UVabsorbing compounds are thermally stable at polyester processingtemperatures, absorb in the range of from about 320 nm to about 380 nm,and are difficult to extract or nonextractable from said polymer. The UVabsorbing compounds preferably provide less than about 20%, morepreferably less than about 10%, transmittance of UV light having awavelength of 370 nm through a bottle wall 12 mils (305 microns) thick.Suitable chemically reactive UV absorbing compounds include substitutedmethine compounds of the formula

wherein:

-   -   R is hydrogen, alkyl, substituted alkyl, aryl, substituted aryl,        cycloalkyl, substituted cycloalkyl or alkenyl, or a        polyoxyalkylene chain, such as polyoxyethylene or        polyoxypropylene polymers, each optionally having some        oxypropylene or oxyethylene units in the polymer chain as a        block or random copolymer, the polyoxyalkylene chain having a        number average molecular weight ranging from 500 to 10,000;

R¹ is hydrogen, or a group such as alkyl, aryl, or cycloalkyl, all ofwhich groups may be substituted;

R² is any radical which does not interfere with condensation with thepolyester, such as hydrogen, alkyl, substituted alkyl, allyl, cycloalkylor aryl,;

R³ is hydrogen or 1-3 substitutents selected from alkyl, substitutedalkyl, alkoxy, substituted alkoxy and halogen, and

P is cyano, or a group such as carbamyl, aryl, alkylsulfonyl,arylsufonyl, heterocyclic, alkanoyl, or aroyl, all of which groups maybe substituted.

Preferred methine compounds are those of the above formula wherein: R²is hydrogen, alkyl, aralkyl, cycloalkyl, cyanoalkyl, alkoxyalkyl,hydroxyalkyl or aryl; R is selected from hydrogen; cycloalkyl;cycloalkyl substituted with one or two of alkyl, alkoxy or halogen;phenyl; phenyl substituted with 1-3 substitutents selected from alkyl,alkoxy, halogen, alkanoylamino, or cyano; straight or branched loweralkenyl; straight or branched alkyl and such alkyl substituted with 1-3substitutents selected from the following: halogen; cyano; succinimido;glutarimido; phthalimido; phthalimidino; 2-pyrrolidono; cyclohexyl;phenyl; phenyl substituted with alkyl, alkoxy, halogen, cyano, oralkylsufamoyl; vinyl-sulfonyl; acrylamido; sulfamyl;benzoylsulfonicimido; alkylsulfonamido; phenylsulfonamido;alkenylcarbonylamino; groups of the formula

where Y is —NH—, —N-alkyl, —O—, —S—, or —CH₂O—; —S—R₁₄; SO₂CH₂CH₂SR₁₄;wherein R₁₄ is alkyl, phenyl, phenyl substituted with halogen, alkyl,alkoxy, alkanoylamino, or cyano, pyridyl, pyrimidinyl, benzoxazolyl,benzimidazolyl, benzothiazolyl; or groups of the formulae

—NHXR₁₆, —CONR₁₅R₁₅, and —SO₂NR₁₅R₁₅;wherein R₁₅ is selected from H, aryl, alkyl, and alkyl substituted withhalogen, phenoxy, aryl, —CN, cycloalkyl, alkylsulfonyl, alkylthio, oralkoxy; X is —CO—, —COO—, or —SO₂—, and R₁₆ is selected from alkyl andalkyl substituted with halogen, phenoxy, aryl, cyano, cycloalkyl,alkylsulfonyl, alkylthio, and alkoxy; and when X is —CO—, R₁₆ also canbe hydrogen, amino, alkenyl, alkylamino, dialkylamino, arylamino, aryl,or furyl; alkoxy; alkoxy substituted with cyano or alkoxy; phenoxy; orphenoxy substituted with 1-3 substitutents selected from alkyl, alkoxy,or halogen substituents; and

-   -   P is cyano, carbamyl, N-alkylcarbamyl, N-alkyl-N-arylcarbamyl,        N,N-dialkylcarbamyl, N,N-alkylarylcarbamyl, N-arylcarbamyl,        N-cyclohexyl-carbamyl, aryl, 2-benzoxazolyl, 2-benzothiazolyl,        2-benzimidazolyl, 1,3,4-thiadiazol-2-yl, 1,3,4-oxadiazol-2-yl,        alkylsulfonyl, arylsulfonyl or acyl.

In all of the above definitions the alkyl or divalent aliphatic moietiesor portions of the various groups contain from 1-10 carbons, preferably1-6 carbons, straight or branched chain. Preferred UV absorbingcompounds include those where R and R¹ are hydrogen, R³ is hydrogen oralkoxy, R² is alkyl or a substituted alkyl, and P is cyano. In thisembodiment, a preferred class of substituted alkyl is hydroxysubstituted alkyl. A most preferred polyester composition comprises fromabout 10 to about 700 ppm of the reaction residue of the compound

These compounds, their methods of manufacture and incorporation intopolyesters are further disclosed in U.S. Pat. No. 4,617,374 thedisclosure of which is incorporated herein by reference. The UVabsorbing compound(s) may be present in amounts between about 1 to about5,000 ppm by weight, preferably from about 2 ppm to about 1,500 ppm, andmore preferably between about 10 and about 500 ppm by weight. Dimers ofthe UV absorbing compounds may also be used. Mixtures of two or more UVabsorbing compounds may be used. Moreover, because the UV absorbingcompounds are reacted with or copolymerized into the backbone of thepolymer, the resulting polymers display improved processabilityincluding reduced loss of the UV absorbing compound due to plateoutand/or volatilization and the like.

The polyester compositions of the present invention are suitable formaking into chips or pellets or into a variety of shaped articles.Suitable processes for forming said articles are known and includeextrusion, extrusion blow molding, melt casting, injection molding, meltto mold process, melt to pellet without solid stating, stretch blowmolding (SBM), thermoforming, and the like. There is also provided apolyester polymer composition in the form of a pellet, a bottle preform,a stretch blow molded bottle, a flake, or a chip, wherein the polyesterpolymer composition in its particular form or shape has a b* colorbetween −5 to +5 CIELAB units and a L* brightness of at least 70 CIELABunits in which the melt to make the polyester polymer melt phase productof the composition is reacted and formulated according to the process ofthe invention.

The articles can be formed from the melt phase products by anyconventional techniques known to those of skill. For example, melt phaseproducts, optionally solid state polymerized, which are crystallized toa degree of crystallization of at least 25%, are transported to amachine for melt extruding and injection molding the melt into shapessuch as preforms suitable for stretch blow molding into beverage or foodcontainers, or rather than injection molding, merely extruding intoother forms such as sheet. The process for making these articlescomprises:

e) drying pellets comprising melt phase products having a degree ofcrystallinity of at least 25% and an It.V. of at least 0.7 dL/g andantimony containing residues, optionally but preferably substantiallyfree of titanium containing residues, in a drying zone at a zonetemperature of at least 140° C.;

-   -   f) introducing the pellets into an extrusion zone and forming a        molten polyester polymer composition; and    -   g) forming a sheet, strand, fiber, or a molded part directly or        indirectly from the extruded molten polyester polymer having a        b* ranging from −5 to +5 and an L* of at least 70.

It is preferred that these pellets have not been subjected to a solidstate polymerization step for increasing their molecular weight. In thispreferred embodiment, the pellets which are prepared for introductioninto an extruder are not solid stated, yet have an It.V. sufficientlyhigh such that the physical properties are suitable for the manufactureof bottle preforms and trays.

Dryers feeding melt extruders are needed to reduce the moisture contentof pellets. Moisture in or on pellets fed into a melt extrusion chamberwill cause the melt to lose It.V. at melt temperatures by hydrolyzingthe ester linkages with a resulting change in the melt flowcharacteristics of the polymer and stretch ratio of the preform whenblown into bottles. It is desirable to dry the pellets at hightemperatures to decrease the residence time of the pellets in the dryerand increase throughput. Drying may be conducted at 140° C. or more,meaning that the temperature of the heating medium (such as a flow ofnitrogen gas or air) is 140° C. or more. The use of nitrogen gas ispreferred if drying is conducted above 180° C. to avoid oxidativethermal degradation. In general, the residence time of pellets in thedryer at 140° C. or more will on average be from 0.5 hours to 16 hours.Any conventional dryer can be used. The pellets may be contacted with acountercurrent flow of heated air or inert gas such as nitrogen to raisethe temperature of the pellets and remove volatiles from inside thepellets, and may also be agitated by a rotary mixing blade or paddle.The flow rate of the heating gas, if used, is a balance between energyconsumption, residence time of pellets, and preferably avoiding thefluidization of the pellets. Suitable gas flow rates range from 0.05 to100 cfm for every pound per hour of pellets discharged from the dryer,preferably from 0.2 to 5 cfm per lb. of pellets.

Once the pellets have been dried, they are introduced into an extrusionzone to form a molten polyester polymer composition, followed byextruding the molten polymer into a sheet or film or forming a moldedpart, such as a bottle preform through injecting the melt into a mold.Methods for the introduction of the dried pellets into the extrusionzone, for melt extruding, injection molding, and sheet extrusion areconventional and known to those of skill in the manufacture of suchcontainers.

At the melt extruder, other components can be added to the extruder toenhance the performance properties of the pellets. These components maybe added neat to the bulk polyester pellets or in a liquid carrier orcan be added to the bulk polyester pellets as a solid polyesterconcentrate containing at least about 0.5 wt.% of the component in thepolyester polymer let down into the bulk polyester. The types ofsuitable components include crystallization aids, impact modifiers,surface lubricants, stabilizers, denesting agents, compounds,antioxidants, ultraviolet light absorbing agents, metal deactivators,colorants, nucleating agents, acetaldehyde lowering compounds, reheatrate enhancing aids, sticky bottle additives such as talc, and fillersand the like can be included. All of these additives and many others andtheir use are well known in the art and do not require extensivediscussion.

While an embodiment has been described for the drying of pellets whichhave not been solid stated, it is also contemplated that pellets whichhave optionally been solid stated are also dried at temperatures of 140°C. or more. Examples of the kinds of shaped articles which can be formedfrom the the melt phase products and the polyester polymer compositionof the invention include sheet; film; packaging and containers such aspreforms, bottles, jars, and trays; rods; tubes; lids; and filaments andfibers. Beverage bottles made from polyethylene terephthalate suitablefor holding water or carbonated beverages, and heat set beverage bottlesuitable for holding beverages which are hot filled into the bottle areexamples of the types of bottles which are made from the crystallizedpellet of the invention. Examples of trays are those which are dualovenable and other CPET trays.

This invention can be further illustrated by the additional examples ofembodiments thereof, although it will be understood that these examplesare included merely for purposes of illustration and are not intended tolimit the scope of the invention.

EXAMPLES

The following apply to all the examples and comparative examples. Thestarting oligomeric mixture employed in the polycondensations throughoutall the examples, unless otherwise noted, was prepared from terephthalicacid, ethylene glycol, about 1.5 mole percent of about 35% cis/65% trans1,4-cyclohexanedimethanol, and about 1.2-1.3 weight percent ofdiethylene glycol generated during esterification. The conversion ofacid groups was about 95% by NMR/titration carboxyl ends groups. TheM_(n) of the oligomeric mixture was about 766 g/mole, and the M_(w) wasabout 1478 g/mole. All of the high IV polyesters in the examples weremade exclusively in the melt phase, i.e., the molecular weight of thepolyester polymer melt phase products as indicated by their Ih.V. werenot increased in the solid state.

In the titanium catalyzed samples, the following test procedure wasused. For polycondensation, the ground oligomer (103 g) is weighed intoa half-liter, single-necked, round-bottomed flask. The catalyst solutionadded to the flask is titanium tetrabutoxide in n-butanol. A 316 Lstainless steel paddle stirrer and glass polymer head were attached tothe flask. After attaching the polymer head to a side arm and a purgehose, two nitrogen purges are completed. The polymerization reactor isoperated under control of a CAMILE™ automation system, programmed toimplement the following array.

Stir Time Temp. Vacuum Speed Stage (min.) C.° (torr) (rpm) 1   0.1 270730  0 2 10 270 730  150* 3  2 270 140  300* 4  1 270 140 300 5 10 270 25* 300 6 10 270  25 300 7  1 270  140* 300 8  2 270 140 300 9  1 270 25* 300 10 10 270  25 300 11  2 270   2*  30* 12  1 270    0.5*  30 13500# 270    0.5  30 *= ramp; #= torque termination when temperature =300° C., change all 270 to 300 (for 285° C., change all 270 to 285).

A molten bath of Belmont metal is raised to surround the flask, and theCAMILE™ is implemented. In this array, a “ramp” is defined as a linearchange of vacuum, temperature, or stir speed during the specified stagetime. The stirring system is automatically calibrated between stages 4and 5. After stage 6 ends, the vacuum level was ramped up to 140 torr,and then a 2 minute additive addition stage (stage 8) begins. Thefinisher stage (13) is terminated according to the stirrer torque. Thepolymer is cooled to ambient temperature. The polymers are chopped andground to pass a 3 mm screen.

The same procedure as set forth above is used to make samples ofantimony catalyzed melt phase products. The experiment varies theantimony level (Sb), vacuum level and temperature. The polymers are madeas described in the previous example except that the catalyst solutionadded to the flask is antimony triacetate in ethylene glycol.

The temperature of polycondensation designated in Table 1 is usedthroughout the entire sequence, i.e., the temperature in the prepolymerstages and the temperature in the finisher stage are the same. Thetarget Ih.V. is 0.80 dL/g ±0.05(corresponding to a calculated It.V. ofabout 0.84 dL/g) An agitator torque target is identified for eachfinisher temperature and each polymerization rig. As the molecularweight and corresponding Ih.V. of the melt increases, its melt viscosityalso increases which is correlated to the torque required by theagitator to turn a revolution. Each run is terminated when the torquetarget on the agitator is achieved three times.

The comparative titanium catalyzed examples are indicated by the letterC following the sample number. The results set forth in Table 1illustrate the effect of antimony and titanium based catalysts,respectively, on the b* and L* colors.

The intrinsic viscosity values reported are the limiting value atinfinite dilution of the specific viscosity of a polymer. The intrinsicviscosity is defined by the following equation:

$\eta_{int} = {{\lim\limits_{C\rightarrow 0}\left( {\eta_{sp}/C} \right)} = {\lim\limits_{C\rightarrow 0}{\ln\left( {\eta_{r}/C} \right)}}}$

-   -   where η_(int)=Intrinsic viscosity        -   η_(r)=Relative viscosity= t _(s) /t _(o)        -   η_(sp)=Specific viscosity=η_(r)−1

Instrument calibration involves replicate testing of a standardreference material and then applying appropriate mathematical equationsto produce the “accepted” I.V. values.Calibration Factor=Accepted IV of Reference Material/Average ofReplicate DeterminationsCorrected IhV=Calculated IhV×Calibration Factor

-   -   The intrinsic viscosity (ItV or η_(int)) may be estimated using        the Billmeyer equation as follows:        η_(int)=0.5[e ^(0.5×Corrected IhV)−1]+(0.75×Corrected IhV)

All of the color results shown in this example are the color of the basepolyester polymer, i.e., no blue or red toners or other toners wereadded, and no stabilizers, reheat additives, acetaldehyde bondingagents, or agents to reduce the antimony compound to antimony metal wereadded to the melt phase. For each of these examples using antimonycatalysts, however, some Sb⁰ metal was generated in situ solely byvirtue of the process temperature and time.

The L*, a* and b* color measurement were obtained according to the testmethods and process described above by grinding the polymer into powderaccording to the method described further above. Crystallinity wasimparted to each polymer upon cooling the polymer from the melt phaseduring solidification. Some of the polymers were analyzed for theirdegree of crystallinity. Each of the polymers are believed to have adegree of crystallinity about or above 25%. The analytical method usedto determine the degree of crystallinity is the DSC method describedfurther above. The results are reported in Table 1.

TABLE 1 Ti Level In Sb Level In Torque Time to Sample ppm target ppmtarget Temp Vacuum Target IhV IhV L* b* % No. (actual) (actual) (deg C.)(torr) (kg * cm) (min) (dL/g) powder powder Crystalinity  1C 5 (5.3) 2702 6.6 223.2 0.781 81.13 10.58 34.3  2C 5 (4.9) 270 0.2 6.1 123.6 0.79578.59 8.65  3 400 (393) 270 0.2 6.6 105.4 0.833 73.27 3.76  4 250 (242)285 1.1 5.46 105.1 0.8 75.46 4.43  5 250 (247) 285 1.1 5.46 84.6 0.81278.74 3.99 39.3  6 250 (246) 285 1.1 5.46 82.9 0.766 77.40 5.62  7 250(246) 285 1.1 6.05 81.5 0.768 75.29 4.90  8 250 (250) 285 1.1 6.05 75.00.773 82.05 6.10  9 250 (243) 285 1.1 6.05 60.0 0.728 78.25 4.84 42 10100 (102) 290 2 4.9 146.8 0.793 80.34 8.55 11C 5 (5)   300 2 4.857 54.80.83 81.73 13.04 33.5 12C 5 (5.1) 300 0.2 5.05 30.1 0.805 82.32 10.55 13400 (379) 300 2 5.05 46.4 0.812 70.23 3.11 37.2 14 400 (380) 300 0.24.857 20.3 0.768 73.81 3.83 15C 15 (14.9) 270 2 6.1 159.0 0.803 81.4012.48 16C 15 (15)   270 0.2 6.6 51.4 0.766 79.49 10.44 17C 10 (9.7)  2851.1 5.46 45.4 0.796 81.85 11.18 18C 10 (10)   285 1.1 6.05 43.4 0.79278.23 10.81 30.4 19C 15 (15)   300 2 5.05 16.2 0.771 78.61 14.00 20C 15(14.8) 300 0.2 4.857 9.5 0.791 82.34 14.15

The b* color of samples catalyzed with low concentrations of titanium(i.e. 5 ppm) at a low reaction temperature of 270° C. was less thansatisfactory as indicated by its high values above 8.5. See examples 1Cand 2C. The residence time to obtain an It.V. of about 0.78 or 0.79 wascut in half from 223 to 123 minutes by decreasing the pressure(increasing the vacuum) from 2 torr to 0.2 torr. The residence time inthe antimony catalyzed samples was less than in samples 1C and 2C atequivalent vacuum levels and similar It.V. by using an appropriateamount of antimony catalyst, a higher reaction temperature, or acombination of appropriate antimony catalyst levels and reactiontemperatures. See examples 3-10. Not only did the reaction proceedquicker to the target It.V in the antimony catalyzed samples, but the b*color of the base polymer was better in each antimony catalyzed samplecompared to samples 1C and 2C at equivalent vacuum levels and similarIt.V. It can also be seen that, in antimony catalyzed samples, a b* ofabout 6 or less can be maintained within a wide processing window, andalso within a large variety of different combinations of vacuum,catalyst concentration, and reaction temperatures.

Attempting to reduce the residence time of the titanium catalyzedsamples by increasing the reaction temperature, the catalystconcentration, or decreasing the pressure, or a combination of theseparameters was successful as seen in comparative examples 11C-12C and15C-20C. However, the increase in catalyst concentration and/or reactiontemperature resulted in the further yellowing of the base polyesterpolymer as seen in the increase in b* values in many cases, or at best,did not result in any improvement in b* color to a value of less than 6.The results show that dropping the titanium level to 5 ppm at highertemperatures designed to decrease the reaction time results in polyesterpolymer having an unacceptably high b*. (See 11C-12C).

The results in Table 1 indicate that the antimony catalyzed polyesterpolymers can be made with a lower b* color on the base polyester polymercompared to titanium catalyzed samples at equivalent inherentviscosities. Moreover, when one adheres to the use of low titanium andlow temperature conditions in titanium catalyzed samples, the residencetime for making the antimony catalyzed samples was significantly shorterbecause in the antimony catalyzed reaction, there exists a wide varietyof antimony catalyst concentrations and higher reaction temperatureswhich can be used without significantly increasing the b* color beyond6.

Example 2

In this series of examples, phosphorus stabilizers were added during themelt-phase synthesis. The type of stabilizer added in all cases was anoligomeric phosphate triester. The amount is varied as shown in Table 2.The lowest phosphorus:metal mole ratio (P:M Z) is zero.

Reheat additives, reducing agents, and toners are not added to the meltin these samples. Each of samples illustrate the P:M Z effect, catalystlevel, and temperature on the b* and the L* of high It.V. polyesterpolymer melt phase products.

A designed experiment varies antimony level (Sb), reaction temperatureand/or the phosphorous/Sb molar ratio. The oligomer charge, equipmentand antimony catalyst solution are the same as described in Example 1.The vacuum level in the finisher reaction zone is fixed at 0.8 torr inall experiments using Sb compounds as the catalyst. The phosphorussolution is added at stage 5, before initiating polycondensation instage 7 and after completing the esterification reactions. Vacuum isapplied at successive stages as stated in the following array.

Stir Time Temp. Vacuum Speed Stage (min.) C.° (torr) (rpm) 1   0.1 270730  0 2 10 270 730  150* 3  2 270 140  300* 4  1 270 140 300 5  2 270140 300 6 10 270  51* 300 7  5 270  51 300 8  1 270    4.5* 300 9 20 270   4.5 300 10  2 270    0.8*  30* 13 500# 270    0.8  30 *= ramp; #=torque termination when temperature = 300° C., change all 270 to 300(for 285° C., change all 270 to 285).

Titanium catalyzed samples are prepared using the same procedure as inthe Sb catalyzed samples, varying the titanium levels, reactiontemperatures, and molar ratios of phosphorus to titanium levels. Theoligomer charge, equipment and antimony catalyst solution are the sameas described in Example 1. The vacuum in the finisher reaction zone isfixed at 0.2 torr. Using the lowest vacuum possible produces the fastesttime to IV, which enables one to better look at the effect of higherP:Ti mole ratios than would otherwise be possible. The phosphoroussolution in the titanium catalyzed samples in this example is added atstage 8 between the first and second prepolymerization zones duringpolycondensation. Vacuum is applied in successive stages as stated inthe following array.

Stir Time Temperature Vacuum Speed Stage Minutes C.° Torr rpm 1   0.1270 730  0 2 10 270 730  150* 3  2 270 140  300* 4  1 270 140 300 5 10270  25* 300 6 10 270 25 300 7  1 270  140* 300 8  2 270 140 300 9  1270  25* 300 10 10 270  25 300 11  2 270    0.2*  30* 12  1 270    0.2 30 13 500# 270    0.2  30 *= ramp; #= torque termination whentemperature = 300° C., change all 270 to 300 (for 285° C., change all270 to 285).

The polyester polymer melt phase product samples are tested for L* andb* at either different reaction temperatures, catalyst levels, and/orvacuum levels. The Ih.V. target for each experiment is 0.8 dL/g. In theTi case, the measured IhV's are within ±0.05 dL/g of the target exceptfor one at 285° C. and two at 300° C. (X28951-168, 169, 187). In the Sbcase, the measured IhV's are within ±0.05 dL/g of the target except forone at 270° C. Table 2 sets forth reaction temperatures, catalystlevels, vacuum levels, phosphorus levels, and L* and b* colors.

TABLE 2 Temp Time to Sample (deg P/M Ti Sb P IV IhV L* % No. C.) Ratio(ppm) (ppm) (ppm) (min) (dL/g) powder b* powder Crystalinity 21C 270 010.0 1.90 59.55 0.749 82.80 9.70 37.8 22 270 0 133 3 182.88 0.762 80.468.12 23 270 0 398 1 75.33 0.726 79.08 3.41 24C 270 0 20.0 1.25 49.500.751 81.45 10.66 25C 270 0.8 18.6 7.90 95.07 0.784 82.10 8.42 26 2700.5 264 35 92.40 0.754 82.01 5.52 40.8 27C 270 1.6 9.5 9.00 302.82 0.76982.76 8.64 38.7 28C 270 1.6 19.0 18.00 268.50 0.750 79.81 8.22 29 270 1130 29 158.84 0.761 84.79 6.81 30 270 1 378 102 120.73 0.765 79.09 4.2931C 285 0 15.0 1.45 22.08 0.785 79.37 10.71 32 285 0 267 3 47.65 0.77876.16 5.23 48.6 33C 285 0.8 10.0 5.50 41.17 0.782 79.98 8.82 38.8 34C285 0.8 10.0 5.50 43.50 0.808 81.88 10.07 38.7 35C 285 0.8 15.1 7.3539.10 0.780 82.76 10.83 36C 285 0.8 14.8 7.60 33.38 0.753 83.68 10.8437C 285 0.8 14.7 7.20 38.45 0.788 81.33 9.93 38C 285 0.8 14.6 7.15 41.900.786 82.15 9.39 39C 285 0.8 14.7 7.20 30.57 0.760 81.54 9.03 40C 2850.8 14.7 7.55 35.62 0.779 81.36 9.20 41C 285 0.8 20.0 9.50 29.95 0.73180.43 9.73 42 285 0.5 133 17 102.30 0.785 80.73 6.02 43 285 0.5 128 2287.24 0.78 83.78 7.72 44 285 0.5 259 33 44.25 0.773 78.74 3.41 45 2850.5 263 32 48.98 0.769 77.74 3.77 46 285 0.5 267 31 42.77 0.759 79.004.63 42.8 47 285 0.5 260 32 49.75 0.771 79.73 4.37 48 285 0.5 264 3452.22 0.782 76.33 2.99 40.3 49 285 0.5 262 34 40.97 0.746 81.79 5.23 50285 0.5 380 50 42.00 0.806 74.13 3.81 51 285 1 261 63 49.35 0.787 76.23.25 26.3 52C 300 0 10.0 1.40 13.95 0.800 82.25 11.82 34.9 53C 300 020.0 1.60 13.72 0.844 80.23 13.92 54 300 0 135 2 44.93 0.755 81.97 9.6055 300 0 388 3 10.62 0.771 77.41 3.16 56C 300 0.8 14.9 7.50 13.00 0.73280.19 11.60 57 300 0.5 262 33 16.78 0.805 77.70 3.43 39.3 58 300 1 13131 36.73 0.788 83.32 6.09 59 300 1 371 90 9.65 0.754 73.62 2.78 60C 3001.6 20.0 19.00 23.08 0.737 83.68 11.49 61C 300 1.6 10.0 8.00 32.95 0.77883.07 11.59 62C 300 1.6 10.0 9.00 33.35 0.781 83.69 10.91 36.4 63C 2851.6 15.0 15.50 90.50 0.853 80.69 10.11

Example 3

This example evaluates the level of colorant that needs to be added to atitanium and an antimony catalyzed fully formulated polyester polymercomposition to obtain similar b* color levels; the effect on L* color bythe addition of the colorant toners, and the reaction time to reachsimilar It.V. levels.

In this example, phosphorus thermal stabilizers are added to polyesterpolymers catalyzed with low levels of titanium (5 ppm) at relatively lowtemperatures (270° C.). When terminating a polymer run at a torqueequivalent to approximately 0.80 IhV, the reaction time was about 155min. The P/Ti mole ratio was at least one. After the 155 minutes ofpolymerization time, the vacuum was broken, the phosphorus compound wasadded, and vacuum was resumed to enhance mixing.

In this example, the phosphorus compound is either phosphoric acid or anoligomeric phosphate triester. To avoid a potential loss in It.V., aconcentrated form of the phosphorus compound was used. By using aconcentrated form of the phosphorus compound, the amount of solventpresent which could hydrolyze or glycolyze the polymer is reduced.Phosphoric acid was added as an 85 weight % solution in water. Thesmallest amount of phosphoric acid that can be reproducibly added byvolume via syringe to the polymer is 0.02 mL, which corresponds to atarget of about 80 ppm P in the polymer. Oligomeric phosphate tri-esterswere added directly as a 9 wt./wt. % phosphorus solution. The smallestamount of the oligomeric phosphate triesters that could be reproduciblyadded by volume via syringe to the polymer was 0.02 mL, whichcorresponds to a target of about 20 ppm P in the polymer.

The following array sets forth the processing conditions for making thetitanium catalyzed polymers using about 5 ppm Ti and using the oligomermixture starting materials and amounts described as in Example 1, exceptthat the oligomeric mixture contained about 1.5 DEG, and the degree ofconversion, with some variance among batches, ranged from about 90% to95%. The phosphorus compounds were added at stage 12. Two polymer runswere made per the following array, one for the addition of phosphoricacid, and one for the addition of oligomeric phosphate triesters.

Time Temp Vacuum Stir Speed Stage minutes C.° torr rpm 1 0.1 270 730 0 210 270 730 150 3 2 270 140 300 4 1 270 140 300 5 10 270 51 300 6 5 27051 300 7 1 270 4.5 300 8 20 270 4.5 300 9 2 270 0.8 30 10 155 270 0.8 3011 3 270 650 30 12 2 270 650 30 13 1 270 0.5 45 14 5 270 0.5 45 * =ramp; # = torque termination when temperature = 300° C., change all 270to 300 (for 285° C., change all 270 to 285).

Typical conditions for polymerizations catalyzed by antimony compoundsare at about 285° C. and about 250 ppm Sb in the polymer. Whenterminating a polymer run at a torque equivalent to approximately 0.80IhV, the reaction time was about 58 minutes. The following array wasused for runs catalyzed by about 250 ppm Sb using the same oligomericmixture as in Example 1, except that the oligomeric mixture containedabout 1.5 DEG, and the degree of conversion, with come variance amongbatches, ranged from about 90% to 95%. The phosphorous compound(s) wasadded in stage 12. Two polymer runs were conducted per the followingarray, one for the addition of phosphoric acid, and one for the additionof oligomeric phosphate trimesters.

Time Temperature Vacuum Stir Speed Stage Minutes C.° torr rpm 1 0.1 285730 0 2 10 285 730 150 3 2 285 140 300 4 1 285 140 300 5 10 285 51 300 65 285 51 300 7 1 285 4.5 300 8 20 285 4.5 300 9 2 285 0.8 30 10 58 2850.8 30 11 3 285 650 30 12 2 285 650 30 13 1 285 0.5 45 14 5 285 0.5 45 *= ramp; # = torque termination when temperature = 300° C., change all270 to 300 (for 285° C., change all 270 to 285).

Table 3 sets forth analytical results comparing the titanium catalyzedand the antimony catalyzed polymers stabilized with phosphoric acid.Blue and red organic toners were added to target a disc b* color targetof about 2 CIELAB units. A small amount (0.0005 g) of black iron oxidefrom Ferro, was added to increase the reheat rate of the Ti-catalyzedpolymer to match the reheat rate of the Sb-catalyzed polymer.

TABLE 3 Red Blue RHI Toner Toner P ItV 3 disc 3 disc 3 disc (Ref. PowderPowder Powder % Catalyst (ppm) (ppm) ppm dL/g L* a* b* 9921W) L* Colora* Color b* Color Crystalinity Ti 7.6 15.2 81 0.809 75.47 −0.99 1.800.99 74.86 −1.35 −2.84 38.1 Sb 6.29 12.58 87 0.848 73.81 0.59 2.97 0.98774.3 −0.41 −2.9 34.7

Table 4 sets forth analytical results comparing the titanium catalyzedand the antimony catalyzed polymers stabilized with an oligomericphosphate tri-ester. Blue and red organic toners were added to target adisc b* color target of about 2 CIELAB units. The reheat rates of theTi-catalyzed polymer matched that of the Sb-catalyzed polymer withintest error; therefore no black iron oxide was added.

TABLE 4 Red Blue RHI Toner Toner P ItV 3 disc 3 disc 3 disc (Ref. PowderPowder Powder % Catalyst ppm ppm ppm dL/g L* a* b* 9921W) L* a* b*Crystalinity Ti 8.69 17.39 15 0.855 75.68 0.03 0.92 0.97 73.69 −0.69 −439.3 Sb 6.69 13.38 18 0.881 77.27 1.19 2.54 0.967 75.91 0.12 −2.62 38.5

When the disc b* color (±2) and reheat are made similar with toners andreheat additives (when needed), less toner was added to the Sb catalyzedpolymer to provide similar b* color. However, the polymer catalyzed with250 ppm Sb at 285° C. has the distinct advantage of a much shorterreaction time than polymer catalyzed by the 5 ppm Ti at 270° C. scenarioto attain the same It.V., while maintaining at least comparablebrightness and yellowness.

Example 4

In example 3, the finisher residence time of the low Ti/low temperatureoption was about 2.7 times longer than that of the option with 250 ppmSb and 285° C. To compare color between the two catalyst systems whenthe finisher residence times are more similar, the titanium level inthis example is increased to 10 ppm and the temperature is kept at 270°C. The following array is used for these runs.

Time Temperature Vacuum Stir Speed Stage minutes C.° torr rpm 1 0.1 270730 0 2 10 270 730 150 3 2 270 140 300 4 1 270 140 300 5 10 270 51 300 65 270 51 300 7 1 270 4.5 300 8 20 270 4.5 300 9 2 270 0.8 30 10 66 2700.8 30 11 3 270 650 30 12 2 270 650 30 13 1 270 0.5 45 14 5 270 0.5 45 *= ramp; # = torque termination when temperature = 300° C., change all270 to 300 (for 285° C., change all 270 to 285).

Under these conditions, the finisher time for Ti-catalyzed runs wasaround 66 min. The smallest amount of the oligomeric phosphate triestersthat was reproducibly added by volume via syringe to the polymer is 0.02mL, which corresponds to a target of about 20 ppm P in the polymer.

In the following table 5, the Sb run is the same one shown earlier inExample 3, using the oligomeric phosphate tri-ester as the phosphorussource (Table 4). The reheat rate of the Ti-catalyzed polymer matchedthat of the Sb-catalyzed polymer within test error; therefore, no blackiron oxide was added. Red and blue toners were added at levelssufficient to target similar b* colors. Table 5 sets forth the resultsanalyzed for a*, b* and L* color.

TABLE 5 Red Blue RHI Toner Toner P ItV 3 disc 3 disc 3 disc (Ref. PowderPowder Powder % Catalyst ppm ppm ppm dL/g L* a* b* 9921W) L* a* b*Crystalinity Ti 9.06 18.13 12 0.816 73.80 0.06 1.84 0.993 74.76 −0.58−4.8 37.2 Sb 6.69 13.38 18 0.881 77.27 1.19 2.54 0.967 75.91 0.12 −2.6238.5

The results indicate that less toners have to be added in an Sbcatalyzed polymer to provide similar b* color to a titanium catalyzedpolymer when the latter is made at similar reaction times. The L*brightness of Sb catalyzed polymer was higher than the L* brightness ofthe titanium catalyzed polymer.

Example 5

To further compare color between the two catalyst systems when thefinisher residence time is more similar, in this case the titanium levelwas kept at 5 ppm while the reaction temperature was increased to 289°C. The following array was used.

Temperature Vacuum Stir Speed Stage Time minutes C.° torr Rpm 1 0.1 289730  0 2 10 289 730  150* 3 2 289 140  300* 4 1 289 140 300 5 10 289 51* 300 6 5 289  51 300 7 1 289    4.5* 300 8 20 289    4.5 300 9 2 289   0.8*  30* 10 48 289    0.8  30 11 3 289  650*  30 12 2 289 650  30 131 289    0.5*  45* 14 5 289    0.5  45 *= ramp; #= torque terminationwhen temperature = 300° C., change all 270 to 300 (for 285° C., changeall 270 to 285).

Under these conditions, the finisher time for the Ti-catalyzed run wasabout 48 minutes. The smallest amount of the oligomeric phosphatetriesters that was reproducibly added by volume via syringe to thepolymer is 0.02 mL, which corresponds to a target of about 20 ppm P inthe polymer.

In the following table, the Sb run is the same one shown earlier inExample 3, Table 4. The reheat rate of the Ti-catalyzed polymer matchedthat of the Sb-catalyzed polymer within test error; therefore, no blackiron oxide was added. Red and blue toners were added at levelssufficient to target similar b* colors. Due to the difficultiesencountered in attempting to target similar b*, test variability, or onerun wherein a high amount of phosphorus was added, the results of eachtitanium run are reported. Table 6 sets forth the results analyzed fora*, b* and L* color.

TABLE 6 Red Blue RHI Toner Toner P ItV 3 disc 3 disc 3 disc (Ref. PowderPowder Powder Catalyst ppm ppm ppm dL/g L* a* b* 9921W) L* a* b* %Crystalinity Ti 7.69 15.39 13 0.898 73.80 −0.24 4.19 0.997 73.3 −0.87−2.41 34.1 Ti 7.69 15.39 13 0.899 74.64 −1.18 2.36 0.993 73.69 −1.37 −334.7 Ti 7.69 15.39 25 0.866 75.01 −2.14 1.02 0.996 74.29 −1.91 −2.9634.1 Sb 6.69 13.38 18 0.881 77.27 1.19 2.54 0.967 75.91 0.12 −2.62 38.5

The results indicate that less toner is added to an antimony catalyzedpolymer to provide similar b* color to a titanium catalyzed polymerreacted with comparable fast reaction times. The L* of the Sb catalyzedpolymer was also brighter than the L* of any of the Ti catalyzedpolymers.

1. A process for forming bottle preforms or trays having a b* ranging from −5 to +5 and an L* of at least 70 comprising forming a polyester polymer composition comprising a melt phase product containing antimony residues and having an It.V. of at least 0.70 dL/g; feeding the polyester polymer composition to an extruder; melting the polyester polymer composition to produce a molten polyester polymer; extruding the molten polyester polymer composition through a die; and obtaining bottle preforms or trays having a b* ranging from −5 to +5 and an L* of at least 70; with the proviso that said process does not comprise solid state polymerization.
 2. A process for making polyester polymer articles having a b* ranging from −5 to +5 and an L* of at least 70 comprising: a) forming pellets comprising melt phase products having a degree of crystallinity of at least 25% and an It.V. of at least 0.7 dL/g and comprising antimony containing residues; b) drying said pellets in said drying zone at a temperature of at least 140° C.; c) introducing said pellets into an extrusion zone and forming a molten polyester polymer composition; d) forming a polyester polymer article comprising a sheet, strand, fiber, or a molded part directly or indirectly from the extruded molten polyester polymer; and e) obtaining a polyester polymer article having a b* ranging from −5 to +5 and an L* of at least 70; with the proviso that said prooess does not comprise solid state polymerization.
 3. The process of claim 2, wherein the pellets are substantially free of titanium residues.
 4. The process of claim 2, wherein the melt phase products comprise (a) a carboxylic acid component comprising at least 60 mole % of the residues of terephthalic acid or derivates of terephthalic acid, based on 100 mole percent of carboxylic acid component residues in the product.
 5. The process of claim 2, wherein the polyester polymer article comprise: (a) a carboxylic acid component comprising at least 92 mole % of the residues of terephthalic acid or derivates of terephthalic acid, and (b) a hydroxyl component comprising at least 92 mole % of the residues of ethylene glycol, based on 100 mole percent of carboxylic acid component residues and 100 mole percent of hydroxyl component residues in the polyester polymer melt phase product.
 6. The process of claim 1, wherein the bottle preforms or trays have an L* of 74 or more.
 7. The process of claim 1, wherein the bottle preforms or trays have an L* of 76 or more.
 8. The process of claim 2, wherein the polyester polymer article has an L* of 74 or more.
 9. The process of claim 2, wherein the polyester polymer article has an L* of 76 or more. 